In addition to following your website’s Google Page Rank, and the number of backlinks pointing to your site, another metric to check when following your website’s search engine optimization progress is called Alexa Rank.
Alexa is a website indexing engine that attempts to measure popularity of websites. Alexa gathers its data on websites as does Google by using ‘searchbots’ that crawl the Web reading and storing data from websites. Like Google, Alexa crawls the Internet, retrieving and storing lots of data about websites and the popularity of websites. However, unlike Google, Alexa builds their popularity rank from data sent to them by people who have installed an Alexa Toolbar into their web browser. If you have the Alexa Toolbar installed into your browser, every time you visit a website, data is sent to Alexa, telling Alexa what websites you have visited. In this way, Alexa is able to build a ranking popularity index of which websites are visited most. The highest, most visited/popular site, has an Alexa Rank of 1, which is currently held by Google. For example, Apple Computer’s main website has an Alexa Rank of 41 and Dell Computer has an Alexa Rank of 200. However, most websites have ranks in the hundreds of thousands or millions.
Google does not make public all the factors that go into how high your website will rank on search results pages, but tracking how your site’s Alexa rank changes over time, whether your Alexa Rank goes up or down, can be an early indicator as to how your website’s Google ranking and search engine results maybe be changing and improving.
A copy of the Alexa database is used for the Internet Archive ( http://waybackmachine.org/ ). Google and Alexa also partner on supporting the Open Directory Project ( http://www.dmoz.org/ ).